How can I install sample-module-payment-gateway (https://github.com/magento/magento2-samples/tree/master/sample-module-payment-gateway) using composer?
I'm getting error "Your requirements could not be resolved to an installable set of packages.", apparently the package name is not recognised.
The documentation only says, that the component should be included in composer, but the how-to is missing?
To clarify: I'm not interested in sample data, but a sample module.